From Incorrect Old-Age, Survivors and Disability Insurance Benefit Payment Computations that Resulted in Overpayments, an audit report by Social Security's Office of Inspector General (OIG):
... SSA makes incorrect benefit computations when employees enter the wrong information into SSA’s systems or incorrectly calculate benefits. Benefits are incorrectly computed when employees or systems base calculations on inaccurate information. When SSA detects an error or obtains accurate information, it corrects the benefits and establishes an overpayment or issues an underpayment. We focused our review on overpayments. ...
We estimate SSA could have avoided approximately 73,000 overpayments totaling more than $368 million if it had effective controls over benefit-computation accuracy. SSA’s controls did not always ensure the Agency calculated benefits accurately. ...
OK, those overpayments aren't good but what about the other side of the coin. Wasn't Social Security as likely to underpay claimants as overpay them? How many claimants were underpaid and by how much? Isn't that as least as important?
This report is a microcosm of OIG's priorities and not just under the current Inspector General -- an intense focus on overpayments with only a limited interest in underpayments, which are at least as big a problem.